As the price for fossil fuels steadily increases and the awareness of the potentially adverse environmental impact of burning fossil fuels grows, solar power is more often looked to as an alternative source of cheap, clean energy. While photovoltaic cells can convert solar energy directly into electricity for virtually any use, such cells remain relatively expensive. Also, energy losses during the conversion and subsequent use of the electricity reduce the overall efficiency of systems employing photovoltaic cells.
An alternative method of harnessing solar energy involves using solar energy to directly heat water, or another fluid. Early systems of this type typically employ solar panels, formed of tubing arranged in blankets, placed on the exterior of a roof. Water is pumped up to the panels where it absorbs radiant heat from solar energy impacting on the roof and is then returned for use or storage. There are several disadvantages to such systems. For instance, building owners may find the roof-mounted components aesthetically unappealing, and may be limited to roofing types that provide a suitable mounting surface for the roof-mounted components. Also, periodic re-roofing generally requires complete removal of the roof-mounted components, thus increasing costs. Secure mounting usually requires penetration of the roof, increasing the risks of a leaky roof during adverse weather conditions.
Since a significant portion of the solar energy impacting on a roof will be transmitted through the roofing material, an alternative solution is to mount the solar heating system under the roof. Existing systems of this type largely solve the problem of aesthetics, but Applicant has found such systems to present other problems that increase the time and cost required to install and maintain such systems, as well as costs associated with roof repair and replacement in the vicinity of such systems.
A relatively recent example of a system of this type is found in U.S. Patent Application Publication No. 2005/0199234. In one embodiment of this system, tubing is secured to a roof by a plurality of support members, which are each attached directly to the underside of the roof. Thus, each support member must be separately formed. Likewise, installation requires the time consuming attachment of each support member and replacement of the tubing requires each support member to be removed.
Additionally, attachment of the support members risks completely penetrating the roof, resulting in damage to roofing materials and leaks. Moreover, installation or replacement of the roofing materials over the system, such as replacement of shingles, would likely result in damage to the support members or tubing, for instance by roofing nails dislodging support members or penetrating tubing. If the roofing material to which the support members were mounted required replacement, for example the plywood sheathing under shingles, the support members and tubing would have to be removed and re-installed.
In another embodiment of the '234 Publication, a plurality of fastening legs are all connected to a single support member. While such an arrangement avoids the need to attach the legs directly to the roof, the fastening legs still abut the roof resulting in likely interference with roofing installation or replacement. Additionally, the fastening legs must still be formed separately and attached to the support member, and replacement of tubing requires removal of the support member, together with all of the fastening legs, from their position adjacent to the roof.